Eagle chain riding on top of cog

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Eagle chain riding on top of cog
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flag provin1327
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Posted: Sep 30, 2019 at 15:06 Quote
I've recently noticed my GX Eagle drivetrain is skipping and popping when I shift into the 42t cog (second to largest). I put the bike in the bike stand and noticed the chain is actually riding on top of the cog like in the picture below.

photo


This problem started after I removed the cassette from the freehub body to grease the pawls. I figured the problem started because the cassette was not in the exact same spot as it was when I removed it so I decided to reset the cable tension, b limit screws (set at sag with the tool) and high and low limit screws.I also made sure the hanger was straight. I originally thought it had too high of cable tension and was getting snagged by the 50t cog during the upshift into the 42t cog but once I put it on the bike stand I noticed that is not the case. The tension is spot on and it shifts great in every other gear. The rear derailleur is practically brand new as I had to replace it due to a crash about 3 months ago.

Has anyone else run into this? The cassette has maybe 800 miles on it. The chain was replace at 600 miles due to being stretched and shifting poorly. The cable and cable housing were also replaced a few months ago. It seems like the Eagle system shifts great when it's brand new but if anything is just a few millimeters out of alignment or just a bit dirty it shifts poorly.
flag brassinne
Posted: Nov 15, 2019 at 20:31 Quote
I also have GX ( first sram drivetrain in 10 years) and have had this happen to me a couple times. Not while riding, but in the bike stand. I can't say that I'm very impressed with the way it operates in general. It's ok at best. On the bike stand, it will make strange clunking sounds at times somewhere around the 8th and 9th gear. However, on the trail it doesn't make any unusual sounds and seems to shift just fine. But still pretty clunky. My last drivetrain was a shimano saint 10 speed on my DH bike and it shifted so much better and was dead silent in comparison. So maybe I am not able to answer your questions, but this has been my GX experience. I have considered upgrading to an AXS cassette and chain with XO shifter and derailleur, but I could simply convert everything to shimano XT for half the cost. So that's most likely the route I will take.
flag provin1327
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Posted: Nov 18, 2019 at 12:43 Quote
brassinne wrote:
I also have GX ( first sram drivetrain in 10 years) and have had this happen to me a couple times. Not while riding, but in the bike stand. I can't say that I'm very impressed with the way it operates in general. It's ok at best. On the bike stand, it will make strange clunking sounds at times somewhere around the 8th and 9th gear. However, on the trail it doesn't make any unusual sounds and seems to shift just fine. But still pretty clunky. My last drivetrain was a shimano saint 10 speed on my DH bike and it shifted so much better and was dead silent in comparison. So maybe I am not able to answer your questions, but this has been my GX experience. I have considered upgrading to an AXS cassette and chain with XO shifter and derailleur, but I could simply convert everything to shimano XT for half the cost. So that's most likely the route I will take.

We are not alone in this. I dug up a big thread on MTBR about the same topic https://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/sram-eagle-design-flaw-1052658.html

I rode yesterday and I am still getting clunky shifts and am "banging" into the 50t cog on upshifts even after taking the advice in the aforementioned MTBR thread to move the chain one tooth forward on the cassette. It doesn't happen all the time but I'd say one out of every five shifts is clunky. It's only an issue going from 42 to 50 though. Shifting up and down through all other gears is fine.

IMO GX Eagle (can't speak for any of the other levels) shifts great when it's brand new and when it's in the vacuum of a repair stand or design table. Once you put it on a bike and throw it out in the real world it does not perform. I wish Shimano did not come up with their new freehub standard or else I'd have already upgraded to XT 12 speed. I've put maybe 700 miles and one single season on my GX Eagle drivetrain and have already had to replace a chain, a derailleur, and now it looks like the cassette may be going too....
flag brassinne
Posted: Nov 18, 2019 at 15:08 Quote
The microspline is also my only real issue at this moment. I'm basically waitting in hopes that Hope releases a microspline freehub. Once that happens, XT it is.
flag provin1327
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Posted: Nov 19, 2019 at 8:48 Quote
brassinne wrote:
The microspline is also my only real issue at this moment. I'm basically waitting in hopes that Hope releases a microspline freehub. Once that happens, XT it is.

Me too but that still means making the switch to 12 speed XT requires a new freehub body or an entirely new freehub, new cassette, new chain, new derailleur, new shifter, new cranks, and new bottom bracket... Do I hate Sram enough to spend that much money and that much effort to go to 12 speed XT?
flag brassinne
Posted: Nov 19, 2019 at 15:45 Quote
provin1327 wrote:
brassinne wrote:
The microspline is also my only real issue at this moment. I'm basically waitting in hopes that Hope releases a microspline freehub. Once that happens, XT it is.

Me too but that still means making the switch to 12 speed XT requires a new freehub body or an entirely new freehub, new cassette, new chain, new derailleur, new shifter, new cranks, and new bottom bracket... Do I hate Sram enough to spend that much money and that much effort to go to 12 speed XT?
I'm not sure why you would have to change the crankset. But, obviously everything else would have to go. The way I see it, I would like to get another set of wheels anyways. So when I do, I'd like to get some hope hubs. I have used them for years and am very happy with their price and performance. The cost of an XO or XX1, AXS cassette alone is roughly the same cost as a XT derailleur, shifter and cassette. So for me, I'd be willing to sell my whole GX drivetrain for a good price and use it to get XT drivetrain components.
flag AngryFranks
Posted: Aug 30, 2020 at 1:57 Quote
Has anyone found a solution to this issue aside from buying Shimano?
I've got the same problem on an XO1 derailleur and cassette.
Going to try and get the LBS to help me warranty it as the place i bought it has closed down, which makes it that much more of a challenge.
Any help MUCH appreciated.
flag chrsei
Posted: Aug 30, 2020 at 10:04 Quote
You can just replace the SRAM derailleur and shifter with XT and it will work fine with SRAM chain and cassette. However the XT seems to require a slightly longer chain. It won't be the super smooth shifting you get with hyper glide but similar to SRAM. Personally, I don't like the XT shifter, the paddles just don't seem to be in the right place and it takes quite a bit more force to shift.

The problem with the chain riding the teeth normally does not happen when under load, just apply the brake a bit when testing and it should be fine. SRAM needs a totally straight derailleur hanger, even a slight bend will cause OK shifting in the smaller gears but skipping in the bigger ones. A derailleur hanger alignment tool is a good investment, or a bike shop can do this. Even new hangers can be slightly off.
flag whatisthecolour
Posted: Mar 21, 2021 at 12:28 Quote
Theres quite a lot of topics about this on other forums over the years.
The two biggest gog teeth have a narrow wide profile and it seems to happen if the chain gets out if sync with the NW teeth. Back pedaling seems to sort it for me. It tends to happen when the b-gap adjustment isn't quiet right too.
flag provin1327
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Posted: Mar 21, 2021 at 12:28 Quote
Philosofize wrote:
No answer yet?

What are you referring to?

I got fed up with the POS Sram GX Eagle and replaced everything with Shimano XT 12 speed. After 1 season and 1,000 miles on Shimano XT 12 speed its still running buttery smooth and the chain is still only showing 5% wear. The shifting is so so much smoother than Sram GX Eagle and the shifting under load is night and day different, so much smoother and silent on Shimano XT.
flag whatisthecolour
Posted: Mar 21, 2021 at 13:07 Quote
provin1327 wrote:
Philosofize wrote:
No answer yet?

What are you referring to?



I would guess it was regarding the OP issue....


I should have mentioned I only ever really noticed this happening while the bike was in the stand.

If it happened while riding I would feel a sudden clunk hich was the chain slipping down into the NW teeth.

I have xx1 axs so it happens across all eagle groupsets.

I feel that the eagle cassettes simply aren't as good as shimano.

I've got a 12 speed shimano cassette and chain that I'm going to run with axs mech to get best of both worlds
flag PNWTommy
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Posted: Apr 4, 2021 at 9:51 Quote
Just hopping on to say that I had the exact same issue as OP, found this thread helpful, and solved it with some very minor b screw adjustment (slight tightening).
flag johnfromthenorth
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Posted: Apr 16, 2021 at 13:54 Quote
I've finally gotten my bike built (XO1 12 speed w/50T cassette) and am experiencing this also.

Have maybe 7 rides/50 miles on the drivetrain and was having intermittent issues with the 2nd largest cog (42T) and chain settling onto cog teeth (skip/clack and periodically ride on top).

Noticed it on the first couple rides (felt/sounded like skipping), but after a couple cable adjuster tweaks, I didn't notice it as much while riding - again all issues are only on the 42T cog.

Well, after having to replace my rear triangle yesterday, I reinstalled the chain and low and behold - the issue is back.

Trying to trouble shoot and it seems like this is all an upper pulley alignment issue. I can get the chain to shift cleanly into, and out of, the 42T by adding more cable tension - but then I lose shifting performance/alignment on the smaller cogs.

Have set b-tension at sag with the "white" tool per Sram and have gone half a turn of the screw in either direction with no real change in performance.

However, if I apply pressure to the upper pulley at the mounting bolt (pushing in towards wheel) - shifting is flawless. I'm talking about a tiny amount of pressure inward. Doesn't appear to me that the XO1 upper pulley is floating (as I recall old Shimano stuff being) and wonder if this is the issue? Just something about the chain line to pulley relationship on that cog, that the system just doesn't like?

Currently considering a putting a little more pressure on it to bend the alignment permanently to see if that works. Again - all other gears (including 50T) have worked flawlessly before and during troubleshooting.

Curious if anyone else can validate this behavior (slight inward pressure on upper pulley mount during shifting takes care of issue).
flag MoeItDown
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Posted: May 16, 2021 at 17:53 Quote
PNWTommy wrote:
Just hopping on to say that I had the exact same issue as OP, found this thread helpful, and solved it with some very minor b screw adjustment (slight tightening).
Thank you for that, I started looking into it more and it looks like thats most likely the problem for the chain not going in all the way in the 50T and the 42T cog. You just need a chaingap adjustment guide (which is only like $10) and a allen key. I'm going to pick one up and then adjust it and see if thats the problem on my X01.
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